If you want just a first introduction to what a framework is and what viewpoints are, you can familiarize yourself with DoDAF. Any MBSE system describing a US government/defense program will most likely be done with a DoDAF approach. DoDAF is becoming a little outdated though and will likely be superseded by UAF sometime in the future. But DoDAF is pretty easy to wrap your head around just as an intro.
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You'll find some examples in some of the SysML books from Delligatti and Friedenthal, but these are examples of a system documented with SysML. There's also Open MBEE, but I haven't really looked into how they approached their project yet.
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